1. Field of the Invention
The present invention relates generally to walking appliances. The preferred embodiment relates to sole attachments for ski boots, and more particularly to attachments designed to increase the safety and comfort of the skier when walking in the ski boots, e.g. in walking to and from the ski slopes. Still more specifically, the technical advance of the present invention relates to such attachments which have been designed taking into account anatomical correctness, kinetic proportionality and the roll point design concepts described later herein.
2. Description of the Prior Art
Modern ski boots have been designed with skiing performance as the number one design criterion. While some efforts have been made, within the ski boot to itself, to increase skier comfort, one major design element of current ski boots makes walking in the boots extremely uncomfortable and dangerous. That factor is the forward cant which locks the lower leg and ankle in a forwardly inclined position, typically approximately 20.degree. off the vertical.
Anyone who is at all familiar with skiing would immediately recognize that the forward cant creates a very clumsy situation when the boot is not attached to the ski itself and when the skier is walking to and from the slopes, is taking a rest or food break, etc. Because the ankle is locked, the normal ski boot walking techniques are to either plant the foot solidly and at one instant bend the body and upper portion of the leg to accommodate such an awkward position. Alternately, some skiers will plant the heel of the ski boot first and then "slap" the remainder of the sole down into contact with the walking surface. In either event, the movements are unnatural and create stresses and/or opportunities for stresses which could quickly lead to skier injury in the event the boot were to slip or the skier were to fall.
Many skiers attempt to overcome these problems by loosening their ski boots when not skiing, but that act creates additional opportunities for dangerous injuries, because the support provided by the boot itself is not present when the boot is loosened. Moreover, the wobbly nature of walking which must be employed if the boots are loosened creates an opportunity for both lateral and longitudinal slippage.
Those familiar with skiing will also recognize that the types of walking difficulties discussed above are encountered even when the surface on which the skier walks is relatively flat and non-slippery (for example in a carpeted ski lounge or on flat snow covered terrain). They are even more awkward and dangerous when a skier tries to manipulate stairs, steep hills or icy surfaces, places where potentially injurious stresses on ligaments or joints in the hip and lower spine can be created.
While the problems discussed previously in this section of the specification have been recognized for a number of years, there are no commercially available devices to overcome the problems. The present inventor is aware that ski sole protectors which are claimed to improve traction of the ski boots are being sold. For example, a ski boot appliance for "Improved Traction And Wear Protection" is described in Carey's U.S. Pat. No. 4,299,037, issued Nov. 10, 1981. While the device has and is being commercially sold, it does not accommodate in any manner for the forward cant of modern ski boots. Rather the device is concerned principally with protection of the bottom of the ski boot sole and improving traction by providing a number of studs in a tread design on the bottom surface. Straps are provided at the toe and heel portion for releasably connecting the appliance to the sole and heel of a ski boot.
Other techniques have also been suggested, including using a different type of ski boot having a curved bottom and a rear binding which is elevated to provide the desired degree of cant for skiing. This device is described in U.S. Pat. No. 4,505,057 issued Mar. 19, 1985 to Kiester and entitled "Ski Boot Sole Extension". The bottom provides a rolling action for walking, with the thickest part of the sole being located beneath the arch portion of the boot. A description of the anatomical considerations relevant the design of this device is provided at Columns 1 and 2 of the patent.
Another technique designed to provide a boot which, in its walking position, keeps the leg in a vertical position is described in U.S. Pat. No. 4,542,599 issued Sept. 24, 1985 to Annovi entitled "Ski Boot With A Normalized Sole". In this device, the boot is comprised of two sections, a first foot encasing section in which the foot is maintained in a normal vertical position. A second section of the boot is designed to be attached to the ski and includes an elevated rear surface. When the portions are combined, a forward cant is accomplished. This design provides a safer and more comfortable boot for walking, but requires a specific, new overall design concept which would not be useful at all on existing boots. Moreover, the engagement of the two portions of the boot would appear to be complicated in situations where snow would enter the corrugated portions on the lower portion and the tread of the boot itself. A related patent issued to the same inventor and disclosing the same concept is described in U.S. Pat. No. 4,570,363 issued Feb. 18, 1986.
Devices which include a sole attachment for ski boots and which provide a generally rocking-type movement when the skier walks in boots with the soles attached include those described by Keller in U.S. Pat. No. 4,294,025 issued Oct.13, 1981 and entitled "Sole Attachment For Facilitating Walking38 ; U.S. Pat. No. 4,156,316 issued May 29, 1979 to DeFever and entitled "Ski Boot Attachment"; a "Ski Boot Cover" described by Roosli in his U.S. Pat. No. 3,965,586 issued June 29, 1976; U.S. Pat. No. 3,971,144 issued July 27, 1976 to Brugger-Stuker for "Combination Ski Boot And Walking Sole And Connection Means For Such Combination"; Frey's "Combination Ski Boot Walker And Carrier" described in U.S. Pat. No. 4,199,880 issued April 29, 1980; and U.S. Pat. No. 3,665,620 issued May 30, 1972 to St. Clair for "Walking Method And Apparatus For Ski Boots". The latter device includes a walking member releasably attached at the central portion of the sole of the ski boot. In side view, the attachment resembles a block and the inventor describes how the extension below the surface of the boot can provide a rocking motion and improved safety and comfort for the wearer.
Another approach to the aforementioned problems of walking in ski boots is described in Koniuk's "Boot Accessory" U.S. Pat. No. 4,619,059 issued Oct. 28, 1986. A boot sole is provided with an attachment means and a generally convex lower surface to provide a more comfortable rocking-type action. The inner portion of the ski boot sole includes a deformable material so that the user is able to walk on irregular or inclined surfaces, such as stairs. The deformable material (actually a material which is more deformable than the material from which the sole itself is constructed), is provided in a core like rectangular body extending longitudinally in the ski sole.
Four additional United States Patents also address the problems discussed above. These will be described in slightly greater detail in that, at first glance, the walking attachments appear to be somewhat similar in configuration to that shown in the present invention. None of these walking attachments appear to take into account anatomical correctness, kinectic proportionality nor "roll point" aspects taught herein. In Calkin, et al, U.S. Pat. No. 4,461,104 issued July 24, 1984 for "Removable Walking Attachment For Ski Boots" the boot is provided with a removable, curved sole having heel and toe straps including turnbuckles so that the walking attachments may be used with a variety of sizes of boots. The thickest portion of the sole is located under the ball of the foot to allow the foot to rock rearward, thus enabling the leg to be straightened at the knee for normal walking. The deficiencies of using a single sized device for different ski boots and the particular deficiencies of the configuration of the Calkin, et al device will become apparent after the description of the preferred embodiment of the present invention is read and understood. Calkin, et al, like many of the other patents, provides a tread on the lower surface of the attachment for increasing traction between the ski boot attachment and the surface.
Another "Ski Boot Attachment" is described in the Groves U.S. Pat. No. 4,228,602 issued Oct. 21, 1980. In this device, a wire member is rotatably mounted at the rear of the attachment for coupling the rearward projection of a typical ski boot to the sole, and a spring loaded retractable clamp is used to secure the toe extension to the boot. In cross surface configuration, the attachment is generally convex, but it is slightly thicker at the forward part of the arch or the rearward portion of the ball part of the foot encased within the ski boot.
Yet a further device similar to the previously described patent is the "Ski Boot Walking Accessory" described by Booty in his U.S. Pat. No. 4,286,397 issued Sept. 1, 1981. This patent also includes a tread containing sole attachment having means for connecting the toe and heel extensions of the boot, and specifically an elongate elastically deformable cord which engages the heel portion of the boot. A plurality of stud-engaging slots are provided along the length of the sole to permit a range of adjustment of the effective length of the cord, thus permitting a single size attachment to be used with a variety of sizes of boots. As previously mentioned, the defects inherent in such a design concept will become apparent later in this specification.
Finally, with regard to United States patents, Woolley also discloses in "Combined Holder And Sole Accessory", U.S. Pat. No. 4,160,301 issued July 10, 1975 a combined holder and sole which has a convexly curved ground engaging surface. The curve is alleged to provide or simulate normal ambulatory movement and includes its thickest portion generally at the forward part of the arch, or beneath the ball of the foot. The device of this patent includes a rearward section which is extensible to allow the boot attachment to be used with a variety of sizes of ski boots. This device also includes a tread for improving traction.
As would be expected in the skiing art, the problems described about walking in ski boots have also been addressed by foreign inventors. For example, German Patent No. 27 46 052 also describes a ski boot attachment having a generally convex lower surface to improve walking conditions when a ski boot having a forward cant is used. Other foreign patents of interest include German Patent Nos. 26 17 257, 23 63 131, 26 12 257 and Swiss No. 588,832. Finally, another rocking-type device is disclosed in Swiss Patent No. 573,729. In this device, a central block portion is provided at the midpoint of the attachment and two extensions extend forwardly and rearwardly therefrom. The exensions are locked by deformable cords over the toe and heel of the boot so that the walking action takes place primarily on the block portion.
A most interesting aspect of studying the disclosures of the aforementioned patents is the fact that after reviewing currently available ski acessories, the only commercially available device is the traction device of Carey disclosed at the beginning of this section of the specification. The problems with which the present invention are concerned are so important to the well-being of the skiing community that it is not surprising that the art is crowded with overly simplistic and technically inadequate devices. Because one would expect a desirable solution to the problem to be an instant commercial success among the safety concious, it becomes apparent that the attempted solutions have, in fact, missed the basics required for either commercial or technical success.